The present invention relates to interlocking pavers as may be used to form a pavement, and more specifically to an illuminated interlocking paver.
Pavements made of interlocking pavers have been used for streets, driveways, walkways, and runways. Interlocking pavers are typically made of from a concrete of Portland cement and aggregates, and may support loads greater than 5,000 psi. Interlocking pavers provide a gap-free surface with no long runs of seams between pavers. Furthermore, many pavers have a thickness comparable to the longest inter-paver seam. For example, an octagonal paver with eight 2.5 inch facet edges may be 2 inches thick. The vertical faces of adjacent pavers support each other in the pavement, unlike tiles. The pavers are typically laid on a screed sand base overlaying a compacted aggregate base, providing a load-equalizing surface and water drainage. The support provided between adjacent pavers by the thickness of the pavers allows each paver to move slightly in a vertical direction without significantly tilting the paver when loaded, such as when a vehicle drives across the pavement. This may allow the load to be shared between pavers, as contrasted with a poured concrete pavement, which may crack rather than move.
Interlocking pavers come in a variety of shapes, such as the keyhole shape 100 shown in FIG. 1A. A V-groove 101 allows the square tab 102 to be broken off of the octagon body 103 for edging and other purposes. The keyhole paver 100 of FIG. 1 has a nominal height 150 of 2.36 inches, but may be as thick as nominally 3.15 inches, and a facet edge length 151 of nominally 2.5 inches. Interlocking pavers also come in the shape of hexagons, truncated squares 110, FIG. 1B, to be used with interstitial squares 111, as well as other shapes.
Interlocking paving stones may provide a superior alternative to poured concrete in many situations. For example, desert climates may not provide proper curing conditions for concrete pavements that are poured in place. Pavements or runways in these areas may have improperly-cured surfaces and interior voids that cause the concrete to crack and wear rapidly. Pavers, on the other hand, may be cast in a controlled environment, resulting in up to three times the strength of poured concrete, and installed at the point of use. Similar advantages are enjoyed in cold climates, where pavers may provide greater resistance to freeze-thaw cracking and better water drainage, thus reducing pavement icing.
Another advantage of interlocking pavers over poured concrete is that the pavers may be formed into a pattern for aesthetic or functional purposes. Pavers of different colors or shapes may be used to delineate different regions of a pavement, for example different colored pavers could identify the center line of a driveway. However, it may be difficult to distinguish between the different types of pavers at night. An illuminated paver may be desirable for identifying portions of a pavement at night, such as the center line of a road or the border of a driveway. Illuminated pavers may also improve safety on stair treads and walkways, especially if the heat from the illuminated paver is sufficient to melt accumulated snow.
Some attempts have been made at providing an illuminated paver system. One system forms concrete pavers with vertical through-holes that accept a point-source fiber-optic light fixture. The light fixtures utilize a glass lens that is rated at a maximum load of 992 psi. Each light fixture should be within 50 feet of a central light source. Larger pavements would require multiple light sources, which are expensive. The glass lens is relatively fragile and susceptible to breakage, as when driven over with snow chains or studded tires. Additionally, the small point of light may be difficult to see and provides little lighting power.
Another attempt at providing an illuminated paver system addresses the issue of border pavers. This system provides brick-shaped lamps designed to be installed in the borders of interlocking paver installations. This lamp has a smooth lens surface that may offer very low friction in wet or dusty conditions. The lens also overhangs the cast plastic body of the lamp, precluding the vertical faces of adjacent lamps from providing inter-lamp support, as discussed above. Furthermore, the strength of the lamp may be inadequate to form an illuminated pavement, restricting its use to where it is surrounded by conventional concrete pavers that can support the traffic load.
Therefore, it is desirable to be able to form a pavement of illuminated interlocking pavers. It is further desirable that the interlocking pavers have sufficient strength to support the dynamic or static loads associated with vehicular traffic and provide reasonable traction across the illuminated paver surface. It is further desirable that the illuminated pavers be sufficiently durable to withstand being driven over with tire chains or studded tires, and that the pavers may be illuminated by light sources of differing powers or colors.